An exemplary embodiment relates generally to a semiconductor apparatus, and more particularly to a voltage supply circuit and method of providing a high voltage in a semiconductor apparatus.
Nonvolatile memory devices such as electrically erasable and programmable flash memory devices perform erase operations for erasing data stored in memory cells and program operations for storing data in the memory cells taking advantage of the Fowler-Nordheim (F-N) tunneling and hot electron injection principles.
A flash memory device operates with a low power source voltage but also generates high voltage by having a voltage supply circuit for internally generating a high voltage within a chip. The voltage supply circuit in a flash memory device is configured to output a high voltage by pumping an input low voltage using a voltage pump circuit.
FIG. 1 shows a conventional voltage supply circuit 100 of a nonvolatile memory device.
Referring to FIG. 1, the voltage supply circuit 100 includes a clock generator 110 and a pump group 120.
The clock generator 110 generates a clock CLK in a pulse form ranging from a power source voltage VCC to a ground voltage VSS.
The clock CLK of the clock generator 110 is outputted as a first clock CK and a second clock CKb through first and second inverters A1 and B1 as shown in FIG. 1.
The first inverter A1 inverts the clock CLK and outputs the inverted signal as the first clock CK, and the second inverter B1 inverts the first clock CK and outputs the inverted signal as the second clock CKb. The first and second inverters A1 and B1 invert their respective input signals so that the inputted signals are pulled up or pulled down to the power source voltage VCC and the ground voltage VSS.
The first inverter A1 inverts the clock CLK and outputs the inverted clock as the first clock CK.
The first clock CK is inputted to the second inverter B1. The second inverter B1 inverts the first clock CK and outputs the inverted clock as the second clock CKb.
The pump group 120 includes a plurality of pump circuits such as the first to fourth pump circuits 121 to 124 as shown in FIG. 1.
The pump circuits 121 to 124 have same configuration. Each pump circuit pumps the inputted voltage in response to the first and second clock signals CK and CKb and outputs the pumped voltage.
The pump circuits 121 to 124 are connected in series so as to receive the output voltage of one pump circuit as an input voltage and to output an output voltage to the next pump circuit connected in series. For example, the first pump circuit 121 receives the power source voltage VCC as the input voltage, and each of the remaining pump circuits 122 to 124 receives the voltage outputted from the previous pump circuit as its input voltage. The pump circuits 121 to 124 perform pumping operations, because the first and second clock signals CK and CKb are received in a pulse form between the power source voltage VCC and the ground voltage VSS. That is, the pump circuits 121 to 124 perform the pumping operations according to the voltage difference dt of VCC between the first and second clock signals CK and CKb.
In the voltage supply circuit 100, the pump circuits 121 to 124 of the pump group 120 include respective capacitors (not shown). Furthermore, the capacitors of the pump circuits 121 to 124 are repeatedly charged and discharged in response to the first and second clock signals CK and CKb in order to pump voltage.
To charge and discharge the capacitors in the pump circuits 121 to 124, the first and second clock signals CK and CKb are repeatedly pulled up to the power source voltage VCC and pulled down to the ground voltage VSS.
The first and second inverters A1 and B1 pull up the first and second clock signals CK and CKb to the power source voltage VCC or pull down the first and second clock signals CK and CKb to the ground voltage VSS.
Most of the current consumed by the voltage supply circuit 100 is the current consumed while the first and second clock signals CK and CKb are pulled up or pulled down. That is, the first and second inverters A1 and B1 are responsible for most of the current consumed by the voltage supply circuit 100.
When more pump circuits (for example, the four pump circuits 121 to 124 shown in FIG. 1) are necessary to output a sufficiently high voltage by the pump circuit 120, the more capacitors are needed. Thus, the amount of current consumed to generate the first and second clock signals CK and CKb by the first and second inverters A1 and B1 will increase even more to charge and discharge an increased number of capacitors due to increased number of pump circuits in the pump circuit 120.